Superlative form of thirsty: most thirsty.(adjective)
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Use "thirstiest" in a sentence
"Sacramento is one of the so-called thirstiest cities in the nation, with demand for the limited resource outpacing the precious supply, according to a national magazine."
"For the first month of Ricardo and Felicity's affair, they greeted one another at every stolen rendezvous with a kiss -- a lengthy, ravenous kiss, Ricardo lapping and sucking at Felicity's mouth as if she were a giant cage-mounted water bottle and he were the world's thirstiest gerbil."
"(Small wonder neighboring DC is the thirstiest non-state in the nation.)"